import unittest
import functools
import operator

big = '''
73167176531330624919225119674426574742355349194934
96983520312774506326239578318016984801869478851843
85861560789112949495459501737958331952853208805511
12540698747158523863050715693290963295227443043557
66896648950445244523161731856403098711121722383113
62229893423380308135336276614282806444486645238749
30358907296290491560440772390713810515859307960866
70172427121883998797908792274921901699720888093776
65727333001053367881220235421809751254540594752243
52584907711670556013604839586446706324415722155397
53697817977846174064955149290862569321978468622482
83972241375657056057490261407972968652414535100474
82166370484403199890008895243450658541227588666881
16427171479924442928230863465674813919123162824586
17866458359124566529476545682848912883142607690042
24219022671055626321111109370544217506941658960408
07198403850962455444362981230987879927244284909188
84580156166097919133875499200524063689912560717606
05886116467109405077541002256983155200055935729725
71636269561882670428252483600823257530420752963450
'''

def numerize(string):
	'''return the number represented by a string with leading characher'''
	return int( "".join(line.strip() for line in string) )

def product_of_first_n(string, n):
	'''calculate the ''produttoria'' of first n digits of a string that represent a number'''
	if len(string)<n: raise IndexError # input validation
	intlist = [int(string[i]) for i in range(len(string)) if i<n] # cast and cut
	return functools.reduce(operator.mul, intlist) # function body
		
def pick_n(string,n):
	'''take all possible consecutive character of a string. example: "1234" is ["12", "23", "34"]'''
	while len(string)>n:
		yield string[:n]
		string = string[1:]
# another implementation of pick_n in pre functional python 2.6 from http://pyeuler.wikidot.com
#
#def get_groups(iterable, n, step):
#    """Make groups of 'n' elements from the iterable advancing
#    'step' elements each iteration"""
#    itlist = tee(iterable, n)
#    onestepit = izip(*(starmap(drop, enumerate(itlist))))
#    return takeevery(step, onestepit)

class T(unittest.TestCase):

	def test_total(self):
		################################################## project euler resultion
		global big
		big = big.replace('\n', '')
		products = []
		for i in pick_n(big, 5):
			products.append( (i, product_of_first_n(i,5)) )
		print( max(products, key=lambda x:x[1]) )

	def test_pick_not_consecutive(self):
		string = "12345"
		consecutives = [12, 23, 34, 45]
		count = 0
		for i in pick_n(string, 2):	
			self.assertEqual(int(i), consecutives[count])
			count += 1


	def test_pick_prod(self):
		string = "12121212"
		for i in pick_n(string, 2):
			self.assertEqual(product_of_first_n(i,2), 1*2)

	def test_p5(self):
		string = "12345"
		self.assertEqual( product_of_first_n(string, 2), 1*2 )
		self.assertEqual( product_of_first_n(string, 5), 1*2*3*4*5 )
		self.assertRaises(IndexError, product_of_first_n, string, 10 )

	def test_numrize(self):
		s = '''
			1
			2
			3
		    '''
		self.assertEqual(numerize(s), 123)

unittest.main()


